Duplicate Payments/Invoices

In the past month we have had two issues were a vendor was double paid.  The two scenerios:

1.  Invoice Number and Amount were the same.  However, when the invoice number was keyed, one number was dropped from the invoice number.  So of course, the system did not give us a warning of the same invoice.

2.  Vendor invoice number was different but amount was the same.  They billed us twice for the same period.  Again, the system didn't warn us because the invoice numbers were different.

My question is:  Is there anyway to set up a warning based on the amount invoiced within a given time period?  Say like 90 days.